Underfeed furnace



March 27, 1928.

R. B. MILDON UNDERFEED FURNACE Filed Feb. 6. 1922 INVENTOR.

BY pyzm iaizlz Patented Mar. 27, 1928 REGINALD B. rrrrnon, orLAnsnownn, rnnnsrtvmm, assrgnoniro RILEY sroxnn CORPOBATTO N, A CORPORATION OF MASSACHUSETTS.

mnmnn rvnnaon.

Application. filed February e. 1922. serial no. a4,sa0.-

This invention relates to an underfeed furnace of the type inwhich provision is made for overfeed grates to complete the combustion of the fuel at the rear of the 6 underf'ced retort. I

It is the object of my invention to provide improved devices by which successful operation of the over-feed grates may be effected and by which the air supphed to I different furnace elements may be conveniently and independently cont-rolled.

My invention further relates to arrangements and combinations of-parts which will be hereinafter described and more particula-rly pointed out in the appended claim.

A preferred form of my invention is shown in the drawings in which Fig. 1 is a diagrammatic plan View of an underfeed furnace embodying my improvements; and I Fig. 2 is a side elevation thereof, with certain parts shown in section.

Referring to the drawings, I have shown parts of anunderfeed furnace which is in general of the usual construction and comprises a plurality of retorts 10, separated si fpport tuyere blocks 11 having openings through which air is admitted to the fuel in the retorts 10. Overfeed grate blocks 12 are mounted at the rear and below the retorts 10 and provide for continued combustion of the fuel as it is pushed rearward from the retorts.

The fuel is fed into the retorts at their front ends from a hopper 13 by rams 14 driven from a crank shaft 15, all of these parts being of the usual construction.

At the rear of the overfeed grates 12, dumping plates or fuel supports 16 are mounted for movement about a horizontal axis extending transversely of the retorts.

The plates 16 are preferably of hollow or box-like construction, with air openings or 45 perforations 17 through which air may be admitted to the ash and refuse on the dump ing plates, consuming the last remnants of fuel which may be found therein.

Additional. plates 18 may be mounted on the bridge wall 19, to support the burning fuel or fuel refuse, and extend forward adjacent the plates 16. These plates 18 are shown as having a step like face with perforations in the risers, while the plates 17 show perforations directly in the face of the ,facefor both the plates hollow air-conducting side walls which The structure of'the supporting sur- 16 and 18 should be adapted to the fuel used, some kinds of fuel being poorly adapted to the plain perplate.

forated plates and other kinds presenting no difficulty when "burned thereon.

Air under pressure is supplied to these different parts of the furnace and in the preferred form of my invention separate air supplying means are provided for the tuyere blocks 11, the 'overfeedgrates 12, and the dumping platesv '16 and 18.

A wind trunk 20 extends beneath the retorts 10 and is connected by the hollow re tort side walls to the .tuyere blocks 11. A suitable source of air under pressure, such as. a variable speed fan or blower 21 is con nected bya pipe 22 to the wind trunk 20.

The pipe is also preferably provided with a damper 23 so that the air pressure in the wind trunk 20 may be controlled either :by

regulating the Tspeedof the blower 21 or :by

adjusting the damper '23. 1

A second air trunk or passage 24 extends transversely beneath the furnace and conducts air to the overfeed grates 12 which are provided with suitable air openings as is usual in such constructions. A variable speed fan or blower 25, connection 26 and damper 27 constitute separate means for de livering and controlling the air for the overfeed grates.

A third passage 28 extends transversely beneath the furnace and is connected through openings 29 to the interior of the hollow dumplng plates 16. A variable speed fan 30, connection 31 and damper 32 provide an independent air supply for the air trunk 28. When the rear plates 18 are used, a branch passage 33 and damper 34 may be provided for supplying and controlling the air dehvered thereto. The passage 33 is also shown as connected directly with the trunn1on or hearing of the plates 18, an arrangement optional with that shown for connecting with the plates 16. The usual provision is made for swinging the plates 16 and 18 about their axes for moving or dumping the fueland refuse deposited thereon. Having thus described my invention, it will be seen that I have provided a separate air supply for the tuyere blocks, the overfeed grates, and the dumping plates, and that 'the air supply to each of these furnace elements may be separately controlled either by varying the speed of the fan or blower or by adjusting the damper in the connection between the fan and the furnace. It is thus possible to make the air pressure for the overfeed portions of the furnace either greater or less than for the underfeed portions, adapting the pressure to' whatever conditions of fuel and operation are enthe use of two such separate air supplying furnace,

devices connected to separate parts of the the overfeed grates 12 being omitted. The rear plates 18 may also be omitted in certain combinations and conditions.

Having thusdescribed my invention, it will be evident that changes and modifications can be made therein by thoseskilled in the art within the spirit and scope of my invention asset forth in the claim, and I do not wish to be otherwise limited to the details herein disclosed but what I claim is An underfeed stoker having in combination a fuel retort, means for feeding fuel to said fuel retort,an independently controllable primary air supply, means for conveying air from said primary air supply to the fuel in the upper portion of said retort to Walls enclosing an air chamber, a separate supplemental and independently controllable air supply connected to the interior of the air chamber in said fuel support effective to supply air to the partially consumed fuel thereon for further combustion thereof, t

and another separate supplemental and independently, controllable air supply connected to the interior of the air chamber in said refuse support effective to supply air to the fuel refuse on said support for final combustion thereof, whereby the air pressures in the upper'portion of said retort for initial combustiom'in said fuel support for further combustion, and in said refuse support for final combustion of said fuel may each be Varied and caused to be equal to, greater than or less than the air pressures in the other air-supplied portions of said stoker. 7 7 V In testimony whereof I have hereunto affixed my signature.

REGINALD B. MILDON. 

